import numpy as np

def getInitialisedArray():
    return np.empty((), dtype=np.float).tolist()

def createFloatArray(x):
    return np.array(float(x))

>>> getInitialisedArray()
0.007812501848093234

>>> createFloatArray(3.1415)
3.1415

print(getInitialisedArray())
print(createFloatArray(3.1415))
print(getInitialisedArray())

>>>
0.007812501848093234
3.1415
3.1415

import numpy as np

def getInitialisedArray():
    # Changed size to 2 x 2
    return np.empty((2, 2), dtype=np.float).tolist()

def createFloatArray(x):
    return np.array(float(x))

print(getInitialisedArray())
print(createFloatArray(3.1415))
print(getInitialisedArray())

[[1.6717403e-316, 6.9051865033801e-310], [9.97338022253e-313, 2.482735075993e-312]]
3.1415
[[1.6717403e-316, 6.9051865033801e-310], [9.97338022253e-313, 2.482735075993e-312]]